Why are there different types of concrete stumps and what is their purpose?

Updated: Jun 5

When home improvers visit our concrete products yard in Melbourne, they are presented by 3 different stump styles. What are these different concrete stump types and what is their purpose?

The right concrete stump makes all the difference

Hanging concrete stump, standard (pin) concrete stump or threaded concrete stump? This all depends on the nature of your sub floor project. Choosing the right stump will make a huge difference to your project outcome, and will also determine how easy or difficult installing the stumps will be.

Hanging concrete stumps

Hanging concrete stumps, also known as reblocking stumps are characterised by their small galvanised steel loop at the top of the stump. Whilst these stumps can be used for a wide application of building projects, they are specifically designed for reblocking or restumping an existing home. The space available under an old home is often limited, and access to the top of the timber bearers is restricted by the subfloor materials above (joists and timber floors). The small galvanised loop is ideal for fixing your new concrete stump to the exisiting bearer. Once the old rotten stump is removed and hole is dug clean, a new hanging stump is placed over the hole by hanging the stump on a nail that is placed into the bearer. This allows for easier placement of the stump. Once the stump is hanging over the hole, ensure the flat top of the stump is butted up to the bearer above before filling the hole with concrete.

Threaded concrete stump

Threaded concrete stumps, also known as bolt stumps are characterised by the galvanised all thread rod that protrudes at the top of the stump. The galvanised rod is M10, and also comes with a washer and nut. This type of concrete stump is used by builders and trades across Melbourne for new builds, extensions and decks. With new builds, access to the top of the stump is not restricted. Whilst there are various methods to install this type of stump, many builders prefer to build hurdles (timber supports) over their holes to get their floor bearers in place. Once the timber bearers are level and temporarily positioned over the holes, a hole (approx. 11mm) is drilled through the bearer and the stump rod is placed through the hole. The stump is then secured with the but and washer and is left hanging over the hole until concrete arrives. This is a quick and easy way to get out of the ground, and the nut and washer offer great control and solidness for the builder. The threaded rod protrudes by 150-160mm, ideal for applications where 90-140mm timber bearers are used. If the bearer is shorter, you may choose to cut down the thread. In instances where the bearer is greater than 140mm, you may choose to counter sink the thread nut or use a coupler to extend the length of the rod.

Standard rod concrete stump

Standard rod concrete stumps, also known as pins are characterised by their plain steel rod (usually 6.3mm in diameter) that protrudes through the top of the concrete stump. The rod protrudes by approximately 200mm. This type of concrete stump is often referred to as 'old school' and is used by builders and trades across Melbourne for new builds, extensions and decks. Their application and purpose is identical to that of the Threaded stump, however instead of bolting the stump onto the bearer, the builder will use a hammer to bend the rod over the top of the bearer. Whilst this offers a little less control for the builder, it is a more time efficient method as a few hits with a hammer is quicker than fiddling around with a nut and washer. Using the right stump is critical for success on your next project! Feel free to contact our team if you need further information or have any other questions about which stump to use on your next subfloor project.